Re: Class design question
Re: Class design question
- Subject: Re: Class design question
- From: Andy Armstrong <email@hidden>
- Date: Sun, 13 Feb 2005 19:07:05 +0000
On 13 Feb 2005, at 18:33, Ken Tozier wrote:
If these subclasses literally differ only in the size of the data
they encapsulate then surely you just need a pointer to a variable
sized chunk of memory? But surely they must differ in more than that?
Otherwise what were all the function pointers for in your first
design?
The primary difficulty is that I read and write the data to disk
myself as the files have, at least the potential, to be terabytes in
size. With one exception (variable length strings) The data within a
file is always factored by size, that is, every piece of data in a
file will be the same type and size, but what those types and sizes
are is completely up to the user. The problem I'm running into is in
reading a chunk of data from disk and dispatching it to the correct
decoder.
So you're variable sized chunks of data from a file that may contain
many like sized chunks. What else about the data differs? How complex
is the interface to the data? You haven't really let us know what kind
of thing these chunks of data represent.
Can you tell us more about the problem? What are the twenty different
types of thing (or at least what are some of them - to give us a
flavour).
I'm writing an objective C database application that addresses the
issues I dislike about SQL. The data types generally follow the SQL
table definition capabilities, but my app will have a richer set of
types (ie: built in money, length measure, weight measure and many
others) and will allow for very easy cell level localization.
Is there any reason why you don't just use Foundation classes and
encode them for storage? May we also infer from what you've said
elsewhere that you're not supporting variable length records?
To be honest if you're planning to build a database engine that'll
handle 'terabytes' of data I wouldn't be starting the design work at
this end. If you don't want SQL but you do want a record oriented
database why not something like Berkeley DB with serialised Foundation
objects as fields?
--
Andy Armstrong, hexten.net
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Cocoa-dev mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden